class QDrag#

The QDrag class provides support for MIME-based drag and drop data transfer. More…

Synopsis#

Methods#

def __init__()
def defaultAction()
def dragCursor()
def exec()
def exec_()
def hotSpot()
def mimeData()
def pixmap()
def setDragCursor()
def setHotSpot()
def setMimeData()
def setPixmap()
def source()
def supportedActions()
def target()

Static functions#

def cancel()

Note

This documentation may contain snippets that were automatically translated from C++ to Python. We always welcome contributions to the snippet translation. If you see an issue with the translation, you can also let us know by creating a ticket on https:/bugreports.qt.io/projects/PYSIDE

Detailed Description#

Warning

This section contains snippets that were automatically translated from C++ to Python and may contain errors.

Drag and drop is an intuitive way for users to copy or move data around in an application, and is used in many desktop environments as a mechanism for copying data between applications. Drag and drop support in Qt is centered around the QDrag class that handles most of the details of a drag and drop operation.

The data to be transferred by the drag and drop operation is contained in a QMimeData object. This is specified with the setMimeData() function in the following way:

drag = QDrag(self)
mimeData = QMimeData()
mimeData.setText(commentEdit.toPlainText())
drag.setMimeData(mimeData)

Note that setMimeData() assigns ownership of the QMimeData object to the QDrag object. The QDrag must be constructed on the heap with a parent QObject to ensure that Qt can clean up after the drag and drop operation has been completed.

A pixmap can be used to represent the data while the drag is in progress, and will move with the cursor to the drop target. This pixmap typically shows an icon that represents the MIME type of the data being transferred, but any pixmap can be set with setPixmap() . The cursor’s hot spot can be given a position relative to the top-left corner of the pixmap with the setHotSpot() function. The following code positions the pixmap so that the cursor’s hot spot points to the center of its bottom edge:

drag.setHotSpot(QPoint(drag.pixmap().width()/2,
                        drag.pixmap().height()))

Note

On X11, the pixmap may not be able to keep up with the mouse movements if the hot spot causes the pixmap to be displayed directly under the cursor.

The source and target widgets can be found with source() and target() . These functions are often used to determine whether drag and drop operations started and finished at the same widget, so that special behavior can be implemented.

QDrag only deals with the drag and drop operation itself. It is up to the developer to decide when a drag operation begins, and how a QDrag object should be constructed and used. For a given widget, it is often necessary to reimplement mousePressEvent() to determine whether the user has pressed a mouse button, and reimplement mouseMoveEvent() to check whether a QDrag is required.

See also

Drag and Drop QClipboard QMimeDataDraggable Icons ExampleDraggable Text ExampleDrop Site Example

__init__(dragSource)#

Parameters:: dragSource – QObject

Constructs a new drag object for the widget specified by dragSource.

actionChanged(action)#

Parameters:: action – DropAction

This signal is emitted when the action associated with the drag changes.

See also

targetChanged()

static cancel()#

Cancels a drag operation initiated by Qt.

Note

This is currently implemented on Windows and X11.